1. Field of the Invention
This invention relates to an apparatus for processing color images using two types of color image data, i.e., dot data and color code data, and particularly to a color image processing apparatus and a color printing apparatus suitable for color display and printing.
2. Description of the Related Art
(1) Heretofore, dither image is known as psudo-expression of half-tone image on a monochromatic binary display device, i.e., expression of light and shade image in dot data, as disclosed Kamae and Fukinuki, "Digital Image Communication" Sangyo Tosho, p.44.
(2) Moreover, among conventional techniques for separating color image into brightness data and color data and for transmitting the brightness data in run length coding and color data in color code, there is the CAPTAIN system. The CAPTAIN system is disclosed in an article entitled "Pattern Data and Coloring Unit in CAPTAIN" in page 132 of the above mentioned book.
(3) Furthermore, among prior arts for converting a plurality of color praphic data into raster data in a workstation and for superimposing them in a color printer, there is a color image recording apparatus as disclosed in Japanese Laid-open Patent Application (KOKAI) No. 64-68064.
The dither image described above is an area gradation expression by numbers of dots in a monocharomatic binary display apparatus and thus does not require input of multi-valued data of three primary colors (R,G,B) such as input signals in full color CRT display device and printing devices.
Moreover, in the above CAPTAIN the brightness data and color data are expressed in two types of transmitting codes. Therefore, it is possible to transmit the brightness data and color data in the form of dot data.
Furthermore, in the prior art as disclosed in the above Japanese Laid-open Patent Application, the processing for forming raster data (scanning line signals consisting of multi-valued or analogue signals) from a plurality of color graphic data is performed at the side of host. However, this prior art neither discloses nor suggests that dot data is transmitted transmitting as data between the host and a printer.